This proposal is directed to the study of skeletal fixation using porous metallic composites. Specifically, it is proposed to study the ion metal release, transport phenomenon, and related systemic effects in porous sintered powder composites of cast cobalt chrome (ASTM F-75), wrought cobalt nickel chromiun molybdenum (ASTM F-562), and Ti6A14V (ASTMF-136) alloys. The related organometallic complexes will be isolated and their toxicity assessed using in vitro fibroblast cultures. It is also intended to evaluate the tumor induction risk of porous sintered powder cobalt chrome composite (ASTM F-75) and wrought cobalt-nickel-chromiun-molybdenum (ASTM F-562 also known as MP35N) in solid, powder and porous form. The possibility of bone ingrowth enhancement into fiber titanium composites by the use of hydroxyapatites, tricalcium phosphate, fluorides, bone marrow contents, bone morphogenetic protein and direct current electrical stimulation will be evaluated. It is also proposed to compare the ability of three different titanium porous configurations: fiber titanium composite as a total or partial coating and sintered titanium spheres as a method of fixation of a total hip prosthesis. The ability of bone to remodel and their related effects on the surrounding cortex will be evaluated. An acetabular prosthesis of a hemispherical design will also be evaluated in terms of its potential for bone ingrowth as a means of fixation.